Various different types of processing chambers are available for processing different types of workpieces and substrates. The substrates can comprise, for instance, glass plates, films, ribbons, solar panels, mirrors, liquid crystal displays, semiconductor wafers, and the like. Many different types of processing chambers are available, for instance, for processing semiconductor wafers during the manufacture of integrated circuit chips. The processing chambers can be used to anneal the wafers, carry out chemical vapor deposition, plasma enhanced chemical vapor deposition, etching processes, and other deposition processes.
The chamber typically includes a substrate holder, such as an electrostatic chuck assembly, to hold a substrate during processing. A typical electrostatic chuck includes one or more clamping electrodes covered by a dielectric layer. The clamping electrodes are used to generate an electrostatic clamping force for holding the substrate onto the top surface of the electrostatic chuck. Once a substrate is securely held onto a chuck, a process gas is introduced into a chamber and a plasma is formed to process the substrate. The substrate can be processed by a CVD, PVD, etch, implant, oxidation, nitridation or other process.
In many processes, it is desirable to control the temperature of the substrate during processing. Processes can be optimized, for instance, if the temperature of the substrate is uniform and is increased and decreased at desired rates and to desired maximums and minimums. In some embodiments, it can be desired to divide the substrate into a plurality of heating zones with each heating zone being maintained at different temperatures to compensate for different heating effects across the surface of the substrate during processing of the substrate. For instance, a substrate can include an inner heating zone and a peripheral heating zone with the peripheral heating zone being maintained at a higher temperature than the inner heating zone to compensate for additional heat loss occurring at the periphery of the substrate. In circumstances when adjacent heating zones are maintained at different temperatures, it can be preferable to have an abrupt or steep temperature gradient between adjacent heating zones to more adequately compensate for the varying heating effects during processing.
Thus, a need exists for an electrostatic chuck assembly that allows for the radial tuning or control of the temperature profile across the surface of the substrate and that provides an abrupt temperature gradient between adjacent heating zones.